Ionizing radiation ionising radiation is radiation that carries sufficient energy to detach electrons from atoms or moleculesthereby ionizing them. Gamma raysX-raysand the higher ultraviolet part of the electromagnetic spectrum are ionizing, whereas the lower ultraviolet part of the electromagnetic spectrum and all the spectrum below UV, including visible light including nearly all types of laser lightinfraredmicrowavesand Radioactive Contamination - DJ Army - DJ SFX - Live Set waves are considered non-ionizing radiation.
The boundary between ionizing and non-ionizing electromagnetic radiation that occurs in the Nun Hör, Hagen, Sage Mir, Held - Gunther, Hagen, Gutrune - Richard Wagner - Windgassen*, Stewart*, N is not sharply defined, since different molecules and atoms ionize at different energies.
Typical ionizing subatomic particles found in radioactive decay include alpha particlesbeta particles and neutrons. Almost all products of radioactive decay are ionizing because the energy of radioactive decay is typically far higher than that required to ionize.
Other subatomic ionizing particles which occur naturally are muonsmesonspositronsand other particles that constitute the secondary cosmic rays that are produced after primary cosmic rays interact with Earth's atmosphere.
Cosmic rays may also produce radioisotopes on Earth for example, carbonwhich in turn decay and produce ionizing radiation. Cosmic rays and the decay of radioactive isotopes are the primary sources of natural ionizing radiation on Earth referred to as background radiation.
Ionizing radiation can also be generated artificially by X-ray tubes Radioactive Contamination - DJ Army - DJ SFX - Live Setparticle acceleratorsand any of the various methods that produce radioisotopes artificially.
Ionizing radiation is not detectable by human senses, so radiation detection instruments such as Geiger counters must be used to indicate its presence and measure it. However, high intensities can cause emission of visible light upon interaction with matter, such as in Cherenkov radiation and radioluminescence.
Ionizing radiation is used in a wide variety of fields such as medicinenuclear powerresearch, manufacturing, construction, and many other areas, but presents a health hazard if proper measures against undesired exposure are not followed. Exposure to ionizing radiation causes damage to living tissueand can result in radiation burnscell damageradiation sicknesscancerand death.
Ionizing radiation is categorized by the nature of the particles or electromagnetic waves that create the ionizing effect. These Radioactive Contamination - DJ Army - DJ SFX - Live Set different ionization mechanisms, and may be grouped as directly or indirectly ionizing.
Any charged massive particle can ionize atoms directly by fundamental interaction through the Coulomb force if it carries sufficient kinetic energy. This includes atomic nucleielectronsmuonscharged pionsprotonsand energetic charged nuclei stripped of their electrons. When moving at relativistic speeds these particles have enough kinetic energy to be ionizing, but relativistic speeds are not required.
The first two ionizing sources to be recognized were given special names used today: Radioactive Contamination - DJ Army - DJ SFX - Live Set nuclei ejected from atomic nuclei are called alpha particlesand electrons ejected usually but not always at relativistic speeds, are called beta particles.
Natural cosmic rays are made up primarily of relativistic protons but also include heavier atomic nuclei like helium ions and HZE ions. In the atmosphere such particles are often stopped by air molecules, and this produces short-lived charged pions, which soon decay to muons, a primary type of cosmic ray radiation that reaches the ground and also penetrates it to some extent.
Pions can also be produced Aquellos Oyos Verdes - Ivanildo* - Sax De Ouro large amounts in particle accelerators. Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus.
Alpha particle emissions are generally produced in the process of alpha decaybut may also be produced in other ways. If the ion gains electrons from its environment, the alpha particle can be written as a normal electrically neutral helium atom 4 2 He.
Alpha particles are a hugely ionizing form of particle radiation. When they result from radioactive alpha decay they have low penetration depth. In this case they can be absorbed by a few centimeters of air, or by the skin. More powerful, long range alpha particles from ternary fission are three times as energetic, and penetrate proportionately farther in air. However, this type of radiation is significantly attenuated by the Earth's atmosphere, which is a radiation shield equivalent to about 10 meters of water.
Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nucleisuch as potassium The production of beta particles is termed beta decay.
When something is said to have radioactive contaminationit often means that there are beta particles being emitted from its surface, detectable with a Geiger counter or other radiation detector. When brought into proximity to the beta emitter, the detector will indicate a dramatic increase in radioactivity. When the detector probe is covered with a shield to block the beta rays, the indication will be reduced dramatically.
High-energy beta particles may produce X-rays known as bremsstrahlung "braking radiation" or secondary electrons delta ray as they pass through matter. Both of these can cause an indirect ionization effect. Bremsstrahlung is of concern when shielding beta emitters, as the interaction of beta particles with the shielding material produces Bremsstrahlung.
This effect is greater with material of high atomic numbers, so material with low atomic numbers is used for beta source shielding. The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. When a low-energy positron collides with a low-energy electron, annihilation occurs, resulting in their conversion into the energy of two or more gamma ray photons see electron—positron annihilation. Positrons can be generated by positron emission nuclear decay through weak interactionsor by pair production from a sufficiently energetic photon.
Positrons are common artificial sources of ionizing radiation used in medical positron emission tomography PET scans.
As positrons are positively charged particles they can also directly ionize an atom through Coulomb interactions. Charged nuclei are characteristic of galactic cosmic rays and solar particle events and except for alpha particles charged helium nuclei have no natural sources on the earth. In space, however, very high energy protons, helium nuclei, and HZE ions can be initially stopped by relatively thin layers of shielding, clothes, or skin.
However, the resulting interaction will generate secondary radiation and cause cascading biological effects. If just one atom of tissue is displaced by an energetic proton, for example, the collision will cause further interactions in the body.
This is called " linear energy transfer " LETwhich Hi-Lili, Hi—Lo - Various - We Remember Them Well elastic scattering. LET can be visualized as a billiard ball hitting another in the manner of the conservation of momentumsending both away with the energy of the first ball divided between the two unequally.
When a charged nucleus strikes a relatively slow-moving nucleus of an object Outside The Muthaship - Current - Current space, LET occurs and neutrons, alpha particles, low-energy protons, and other nuclei will be released by the collisions and contribute to the total absorbed dose of tissue.
Indirect ionizing radiation is electrically neutral and therefore does not interact strongly with matter. The bulk of the ionization effects are due to secondary ionizations. An example of indirectly ionizing radiation is neutron radiation. Even though photons are electrically neutral, they can ionize atoms directly through the photoelectric effect and the Compton effect.
Either of those interactions will cause the ejection of an electron from an atom at relativistic speeds, turning that electron into a beta particle secondary beta particle that will ionize many other atoms. Since most of the Radioactive Contamination - DJ Army - DJ SFX - Live Set atoms are ionized directly by the secondary beta particles, photons are called indirectly ionizing radiation.
Photon radiation is called gamma rays if produced by a nuclear reactionsubatomic particle decay, or radioactive decay within the nucleus. It is otherwise called x-rays if produced outside the nucleus. The generic term photon is therefore used to describe both. Modern technologies and discoveries have resulted in an overlap between X-ray and gamma energies.
In many fields they are functionally identical, differing for terrestrial studies only in origin of the radiation. In astronomy, however, where radiation origin often cannot be reliably determined, the old energy division has been preserved, with X-rays defined as being between about eV and keV, and gamma rays as being of any energy above to keV, regardless of source.
Most astronomical " gamma-ray astronomy " are known not to originate in nuclear radioactive processes but, rather, result from processes like those that produce astronomical X-rays, except driven by much more energetic electrons.
Photoelectric absorption is the dominant mechanism in organic materials for photon energies below keV, typical of classical X-ray tube originated X-rays. At energies beyond keV, photons ionize matter increasingly through the Compton effectand then indirectly through pair production at energies beyond 5 MeV. The accompanying interaction diagram shows two Compton scatterings happening sequentially. In every scattering event, the gamma ray transfers energy to an electron, and it continues on its path in a different direction and with reduced energy.
The lowest ionization energy of any element is 3. However, US Federal Communications Commission material defines ionizing radiation as that with a photon energy greater than 10 eV equivalent to a far ultraviolet wavelength of nanometers.
Thus, X-ray radiation is always ionizing, but only extreme-ultraviolet radiation can be considered ionizing under all definitions. The biological effect of ionizing radiation on cells somewhat resembles that of a broader spectrum of molecularly damaging radiation, which overlaps ionizing radiation and extends beyond, to somewhat lower energies into all regions of UV and sometimes visible light in some systems such as photosynthetic systems in leaves.
Although DNA is always Un Certain Je Ne Sais Quoi - Biréli Lagrène Gipsy Project - Move to damage by ionizing radiation, the DNA molecule may also be damaged by radiation with enough energy to excite certain molecular bonds to form Strange Transmissions - The Peter Malick Group Featuring Norah Jones - New York City dimers.
This energy may be less than ionizing, but near to it. A good example is ultraviolet spectrum energy which begins at about 3. Thus, the mid and lower Radioactive Contamination - DJ Army - DJ SFX - Live Set electromagnetic spectrum is damaging to biological tissues as a result of electronic excitation in molecules which falls short of ionization, but produces similar non-thermal effects. To some extent, visible light and also ultraviolet A UVA which is closest to visible energies, have been proven to result in formation of reactive oxygen species in skin, which cause indirect damage since these are electronically excited molecules which can inflict reactive damage, although they do not cause sunburn erythema.
Neutrons have zero electrical charge and thus often do not directly cause ionization in a single step or interaction with matter. However, fast neutrons will interact with the protons in hydrogen via LETand this Radioactive Contamination - DJ Army - DJ SFX - Live Set scatters the nuclei of the materials in the target area, causing direct ionization of the hydrogen atoms.
When neutrons strike the hydrogen nuclei, proton radiation fast protons results. These protons are themselves ionizing because they are of high energy, are charged, and interact with the electrons in matter.
Neutrons that strike other nuclei besides hydrogen will transfer less energy to the other particle if LET does occur. But, for many nuclei struck by neutrons, inelastic scattering occurs. Whether elastic or inelastic scatter occurs is dependent on the speed of the neutron, whether fast or thermal or somewhere in between.
It is also dependent on the nuclei it strikes and its neutron cross section. In inelastic scattering, neutrons are readily absorbed in a type of nuclear reaction called neutron capture and attributes to the neutron activation of the nucleus.
Neutron interactions with most types of matter in this manner usually produce radioactive nuclei. The abundant oxygen nucleus, for example, undergoes neutron activation, rapidly decays by a proton emission forming nitrogenwhich decays to oxygen The short-lived nitrogen decay emits a Dave Greenslade - Cactus Choir beta ray.
This process can be written as:. While not a favorable reaction, the 16 O n,p 16 N reaction is a major Radioactive Contamination - DJ Army - DJ SFX - Live Set of X-rays emitted from the cooling water of a pressurized water reactor and contributes enormously to the radiation generated by a water-cooled nuclear reactor while operating. For the best shielding of neutrons, hydrocarbons that have an abundance of hydrogen are used. In fissile materials, secondary neutrons may produce nuclear chain reactionscausing a larger amount of ionization from the daughter products of fission.
Outside the nucleus, free neutrons are unstable and have a mean lifetime of 14 minutes, 42 seconds. Free neutrons decay by emission of an electron and an electron antineutrino to become a proton, a process known as beta decay : . In the adjacent diagram, a neutron collides with a proton of the target material, and then becomes a fast recoil proton that ionizes in turn. Such photons always have enough energy to qualify as ionizing radiation.
The relevant mechanisms are neutron activationalpha absorptionand photodisintegration. A large enough number of transmutations can change macroscopic properties and cause targets to become radioactive themselves, even after the original source is removed.